$ { \left[\begin{array}{rr}{4} & {0} \\ {-2} & {3} \\ {0} & {1}\end{array}\right]+\left[\begin{array}{rr}{1} & {1} \\ {3} & {-2} \\ {-1} & {-1}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{4}+{1} & {0}+{1} \\ {-2}+{3} & {3}+{-2} \\ {0}+{-1} & {1}+{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{5} & {1} \\ {1} & {1} \\ {-1} & {0}\end{array}\right]}$